Conjectures and Refutations Quotes

“The history of science, like the history of all human ideas, is a history of irresponsible dreams, of obstinacy, and of error. But science is one of the very few human activities — perhaps the only one — in which errors are systematically criticized and fairly often, in time, corrected. This is why we can say that, in science, we often learn from our mistakes, and why we can speak clearly and sensibly about making progress there.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“The war of ideas is a Greek invention. It is one of the most important inventions ever made. Indeed, the possibility of fighting with with words and ideas instead of fighting with swords is the very basis of our civilization, and especially of all its legal and parliamentary institutions.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“The belief that science proceeds from observation to theory is still so widely and so firmly held that my denial of it is often met with incredulity. I have even been suspected of being insincere- of denying what nobody in his senses would doubt.
But in fact the belief that we can start with pure observation alone, without anything in the nature of a theory is absurd; as may be illustrated by the story of the man who dedicated his life to natural science, wrote down everything he could observe, and bequeathed his priceless collection of observations to the Royal Society to be used as evidence. This story should show us that though beetles may profitably be collected, observations may not.
Twenty-five years ago I tried to bring home the same point to a group of physics students in Vienna by beginning a lecture with the following instructions : 'Take pencil and paper; carefully observe, and write down what you have observed!' They asked, of course, what I wanted them to observe. Clearly the instruction, 'Observe!' is absurd. (It is not even idiomatic, unless the object of the transitive verb can be taken as understood.) Observation is always selective. It needs a chosen object, a definite task, an interest, a point of view, a problem. And its description presupposes a descriptive language, with property words; it presupposes similarity and classification, which in their turn presuppose interests, points of view, and problems.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“It is often asserted that discussion is only possible between people who have a common language and accept common basic assumptions. I think that this is a mistake. All that is needed is a readiness to learn from one's partner in the discussion, which includes a genuine wish to understand what he intends to say. If this readiness is there, the discussion will be the more fruitful the more the partner's backgrounds differ.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“But are there philosophical problems? The present position of English philosophy - my point of departure - originates, I believe, in the late Professor Ludwig Wittgenstein's doctrine that there are none; that all genuine problems are scientific problems; that the alleged propositions or theories of philosophy are pseudo-propositions or pseudo-theories; that they are not false (if they were false, their negations would be true propositions or theories) but strictly meaningless combinations of words, no more meaningful than the incoherent babbling of a child who has not yet learned to speak properly.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“What we should do, I suggest, is to give up the idea of ultimate sources of knowledge, and admit that all knowledge is human; that it is mixed with our errors, our prejudices, our dreams, and our hopes; that all we can do is to grope for truth even though it be beyond our reach. We may admit that our groping is often inspired, but we must be on our guard against the belief, however deeply felt, that our inspiration carries any authority, divine or otherwise. If we thus admit that there is no authority beyond the reach of criticism to be found within the whole province of our knowledge, however far it may have penetrated into the unknown, then we can retain, without danger, the idea that truth is beyond human authority. And we must retain it. For without this idea there can be no objective standards of inquiry; no criticism of our conjectures; no groping for the unknown; no quest for knowledge.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“Science must begin with myths, and with the criticism of myths.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“A theory which is not refutable by any conceivable event is nonscientific. Irrefutability is not a virtue of a theory (as people often think) but a vice.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“And it implies that if we respect truth, we must search for it by persistently searching for our errors: by indefatigable rational criticism, and self-criticism.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“The two psycho-analytic theories were in a different class. They were simply non testable, irrefutable. There was no conceivable human behav­iour which could contradict them. This does not mean that Freud and Adler were not seeing certain things correctly: I personally do not doubt that much of what they say is of considerable importance, and may well play its part one day in a psychological science which is testable. But it does mean that those ‘clinical observations’ which analysts naively believe confirm their theory cannot do this any more than the daily confirmations which astrologers find in their practice. And as for Freud’s epic of the Ego, the Super-ego, and the Id, no substantially stronger claim to scientific status can be made for it than for Homer’s collected stories from Olympus. These theories describe some facts, but in the manner of myths. They contain most interesting psychological suggestions, but not in a testable form.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“The method of learning by trial and error—of learning from our mistakes—seems to be fundamentally the same whether it is practised by lower or by higher animals, by chimpanzees or by men of science.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“in philosophy methods are unimportant; any method is legitimate if it leads to results capable of being rationally discussed. What matters is not methods or techniques but a sensitivity to problems, and a consuming passion for them; or, as the Greeks said, the gift of wonder.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“This false epistemology, however, has also led to disastrous consequences. The theory that truth is manifest—that it is there for everyone to see, if only he wants to see it—this theory is the basis of almost every kind of fanaticism. For only the most depraved wickedness can refuse to see the manifest truth; only those who have reason to fear truth conspire to suppress it.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“My argument against a naive form of empiricism was essentially anticipated by Mark Twain. On his first appointment as a reporter, he tells us, the editor of the newspaper instructed him never to report anything unless he could verify it or confirm it by personal knowledge. So he described a social event as follows: 'A woman giving the name of Mrs James Jones, who is reported to be one of the society leaders of the city, is said to have given what purported to be a party yesterday to a number of alleged ladies. The hostess claims to be the wife of a reputed attorney.'

One sees that Mark Twain was quick to realize the silliness of the naive empiricist (verificationist) theory of the sources of our knowledge.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testabilty: some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“Criticism, I said, is an attempt to find the weak spots in a theory, and these, as a rule, can be found only in the more remote logical consequences which can be derived from it. It is here that purely logical reasoning plays an important part in science.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“I found that those of my friends who were admirers of Marx, Freud, and Adler, were impressed by a number of points common to these theories, and especially by their apparent explanatory power. These theories appeared to be able to explain practically everything that happened within the fields to which they referred. The study of any of them seemed to have the effect of an intellectual conversion or revelation, opening your eyes to a new truth hidden from those not yet initiated. Once your eyes were thus opened you saw confirming instances everywhere: the world was full of verifications of the theory. Whatever happened always confirmed it. Thus its truth appeared manifest; and unbelievers were clearly people who did not want to see the manifest truth; who refused to see it, either because it was against their class interest, or because of their repressions which were still 'un-analysed' and crying aloud for treatment.
The most characteristic element in this situation seemed to me the incessant stream of confirmations, of observations which 'verified' the theories in question; and this point was constantly emphasized by their adherents. A Marxist could not open a newspaper without finding on every page confirming evidence for his interpretation of history; not only in the news, but also in its presentation--which revealed the class bias of the paper--and especially of course in what the paper did not say. The Freudian analysts emphasized that their theories were constantly verified by their 'clinical observations'. As for Adler, I was much impressed by a personal experience. Once, in 1919, I reported to him a case which to me did not seem particularly Adlerian, but which he found no difficulty in analysing in terms of his theory of inferiority feelings, although he had not even seen the child. Slightly shocked, I asked him how he could be so sure. 'Because of my thousandfold experience,' he replied; whereupon I could not help saying: 'And with this new case, I suppose, your experience has become thousand-and-one-fold.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“there is no reason to believe that a definition necessarily determines the ontological status of the term defined.)”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“Every ‘good’ scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the better it is.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“in the field of ethics, of moral knowledge, it was approached by Kant with his principle of autonomy. This principle expresses his realization that we must not accept the command of an authority, however exalted, as the basis of ethics. For whenever we are faced with a command by an authority, it is for us to judge, critically, whether it is moral or immoral to obey. The authority may have power to enforce its commands, and we may be powerless to resist. But if we have the physical power of choice, then the ultimate responsibility remains with us. It is our own critical decision whether to obey a command; whether to submit to an authority.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“liberal I do not mean a sympathizer with any one political party but simply a man who values individual freedom and who is alive to the dangers inherent in all forms of power and authority.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“The fundamental mistake made by the philosophical theory of the ultimate sources of our knowledge is that it does not distinguish clearly enough between questions of origin and questions of validity. Admittedly, in the case of historiography, these two questions may sometimes coincide. The question of the validity of a historical assertion may be testable only, or mainly, in the light of the origin of certain sources. But in general the two questions are different; and in general we do not test the validity of an assertion or information by tracing its sources or its origin, but we test it, much more directly, by a critical examination of what has been asserted--of the asserted facts themselves.

Thus the empricist's questions "How do you know? What is the source of your assertion?" are wrongly put. They are not formulated in an inexact or slovenly manner, but they are entirely misconceived: they are questions that beg for an authoritarian answer.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“The way in which knowledge progresses, and especially our scientific knowledge, is by unjustified (and unjustifiable) anticipations, by guesses, by tentative solutions to our problems, by conjectures. These conjectures are controlled by criticism; that is, by attempted refutations, which include severely critical tests. They may survive these tests; but they can never be positively justified: they can neither be established as certainly true nor even as 'probable' (in the sense of the probability calculus). Criticism of our conjectures is of decisive importance: by bringing out our mistakes it makes us understand the difficulties of the problem which we are trying to solve. This is how we become better acquainted with our problem, and able to propose more mature solutions: the very refutation of a theory --that is, of any serious tentative solution to our problem-- is always a step forward that takes us nearer to the truth. And this is how we can learn from our mistakes.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“Moreover, if we could show, on general logical grounds, that the scientific quest is likely to succeed, one could not understand why anything like success has been so rare in the long history of human endeavours to know more about our world.”
― Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge

“At least some of them, I suspect, have turned to probability theory in the hope that it would give them what they had originally expected from a subjectivist or epistemological theory of the attainment of truth through verification; that is, a theory of rational and justifiable belief, based upon observed instances.”
― Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge